1. Field of the Invention
The present invention relates to an intra-subject device loaded within the interior of a subject and a medical device including the intra-subject device, an example of which is a capsule type endoscope. More particularly, the present invention relates to a technology of canceling noise contained in image information, when the image information is radio-transmitted from the intra-subject device or the related medical device thereof.
2. Description of the Related Art
Recently, in the field of the endoscopies, a capsule type endoscope having an imaging function and a radio-communication function has come into practice. The capsule type endoscope, during the time for observation after being swallowed by a subject person for observation (examination) until natural excretion from the living body of the subject, is propelled within the interior of the internal organs such as stomach or small intestine by peristaltic motion of such organs, and takes images of the interior of the organs (inside the body cavity) utilizing the imaging function.
Also, while moving along and observing the organ-interiors, the image data taken by the capsule type endoscope inside the organ are successively transmitted by such a wireless function as radio communication to an external unit or device provided at an outer section of the subject, and such data are stored in a memory provided for the external device. The subject, by carrying the external device having the radio function and the memory function, will be able to behave without any restriction during the observation time from swallowing of the capsule type endoscope until its excretion. After the observation, a physician or nurse will be able to perform diagnoses by displaying the internal images of the body cavity over a structural component for demonstration, such as a display, based on the image data accumulated in the memory of the external device.
Of this kind of capsule type endoscope, for example, there is a swallowable type of endoscope as shown in the Unexamined Patent Publication No. 2002-345743. In this publication, a constitution is proposed wherein a capsule type endoscope is furnished with a built-in battery or cell for supplying electric power, and a LED emits illumination for lighting by the electric power supplied by the battery, an image sensor detects the reflected images from the body cavity of the subject to collectively acquire the image information, and such image information is radio-transmitted from the transmission circuit.
In the above-mentioned capsule type endoscope, for example, if a frequency of transfer clock of an image sensor does not coincide with the frequency of an image signal read-out clock in a signal processing section, picture quality of the image might occasionally deteriorate. On the other hand, if the frequency of the transfer clock of the image sensor does coincide with that of the image signal read-out clock in the image processing section or the like, the edge of the read-out clock conforms to the image signal from the image sensor. Therefore, at least, no such a problem will be encountered.
Nevertheless, since the clock frequency might sometimes be lowered for reducing the current consumption, it may involve a case that the read-out clock be frequency-divided. In that case, for example, a clock edge sometimes appears in every other picture element, thereby causing the clock edge to disaccord with a picture signal from the image sensor. Also, for generation of the above mentioned clock, a switching control is practiced by employing, for example, FET, hence such operation of FET might cause the current consumption to increase at the clock edge, which is a changing point for the clock. There may be a case that a noise tends to migrate into the current source in response to the increased current consumption, thereby affecting the captured picture image and resulting in a problem of deterioration in the quality of the receiving picture.
The present invention has been made in light of the above-mentioned problems, and makes it objective to at least provide an intra-subject device and the related medical device, which are capable of obtaining a high quality signal with lessened noise because the contaminant noise in the image signal is successfully cancelled.